The goal of the AMDCC is to develop animal models of diabetic complications that faithfully reproduce diabetic complications observed in humans. This proposal will provide a model of mouse model of diabetic nephropathy (DN) focusing on two key protective endothelial pathways: eNOS and prostacyclin synthase (PGIS). These pathways are not only co-localized within the endothelial cells but their activity is also biochemically interrelated through cellular levels of peroxynitrate, and both that have been implicated in human diabetic nephropathy, neuropathy, retinopathy and macrovascular disease. In the previous funding cycle, the Vanderbilt AMDCC site investigated the genetic underpinnings of diabetic nephropathy (DN) of mice. Those studies identified systemic eNOS deletion as a critical genetic modifier that converts C57BL/6 mice from a resistant strain to one that is susceptible to DN. Genetic disruption of endothelial nitric oxide synthase (eNOS or NOSIII), but not ApoE or LDLR was associated with a marked acceleration of DN in C57BL/6, not only characterized by a robust albuminuria, but also by dramatic mesangiolysis and expansion with decrease renal function (GFR). The involvement of eNOS as a clinically relevant modifier for risk of human diabetic nephropathy is bolstered by clinical studies showing that diabetics with an eNOS Glu298Asp polymorphism not only exhibit decreased eNOS activity but also an accelerated risk of renal failure {Noiri, 2002 #6975;Shin Shin, 2004 #8934}. Accumulating evidence implicates endothelial dysfunction in the pathogenesis of diabetic complications, particularly nephropathy and macrovascular disease {Schalkwijk, 2005 #9302}. Similarly polymorphisms have been identified in prostacyclin synthase (PGIS), although their specific role in the progression of diabetic nephropathy has not been established, The present proposal has two specific aims: Aim 1 will determine the role of endothelial eNOS in the progression of diabetic nephropathy;while To determine the role of Endothelial prostacyclin synthase in the progression of diabetic nephropathy. To achieve this we will generate conditionally targeted (floxed) eNOS and PGIS alleles, and cross these mice with a Tie2mERCre mouse, allowing temporally controlled deletion of these alleles specifically from the endothelium. These studies should allow the dissection of the role of these biochemical pathways in the progression of diabetic nephropathy in mice.